Diversified electronic systems are one of the most important hardware foundations in the current information society. An electronic system generally integrates chips or devices of various functions with the aid of a circuit board (e.g., a printed circuit board) and/or transmission wires, in a way that data signals are exchanged between the chips to construct overall functions of the electronic system. Therefore, it is a research priority of a chip designer to provide solutions for enabling different chips to smoothly transmit/receive data signals.
To transmit a signal from one chip to another, it is necessary that the chip transmitting the signal have an appropriate signal driving capability, which drives at a receiving end of the chip via traces of the circuit board or/and transmission wires an appropriate signal waveform for representing information contained in the signal. In general, a large driving capability means a small corresponding driving impedance, and vice versa.
Since the driving impedance is a crucial reference and parameter for driving exchange signals in the signal transceiving mechanism, a tolerable range allowed in the driving impedance is established in certain signal exchange interface standards. For example, in the Joint Electron Devices Engineering Council (JEDEC) Double-Data-Rate (DDR) memory signal exchange interface standards, an impedance tolerable range for driving impedance is specified to maintain accuracy in signal exchange. Accompanied with the ever-increasing signal exchange frequency/speed, more limitations are imposed on the driving impedance such that the tolerable range is required to be still ever smaller.
In order to meet requirements in driving impedance, it is necessary to provide a solution for calibrating driving impedance in a current signal transceiving mechanism.